How to verify carbon credits

Every genuine carbon credit has a public trail. It was issued into a registry with a serial number, and when it is used it is retired there, for anyone to see. Checking that trail takes a few minutes and is the best protection against buying something that doesn’t exist or has already been sold. This guide shows you how, registry by registry.

It is part of our Quality section, alongside do carbon offsets work? and carbon credit scams.

What you are checking

One verified credit stands for one tonne of CO₂ equivalent reduced or removed^{Source 1}. To trust that tonne, you need to confirm three things:

1. It exists. The credit was issued by a recognised standard into a public registry, with a unique serial number.
2. It is yours. It has been retired, not just sold, and the record names you or your organisation.
3. It is good. The project and its method of counting tonnes are credible.

The first two you can check in the registry. The third needs a look at the methodology, the CCP label and, if you want more detail, independent ratings.

How to verify a carbon credit, step by step

1. 1

   Step 1: Ask for the serial numbers and registry

   Get the serial numbers or serial range of your credits and the name of the registry that holds them. A seller that can’t give you both is a warning sign.

2. 2

   Step 2: Open the public registry

   Go to the standard’s public registry (listed below) and search for the serial numbers or the project.

3. 3

   Step 3: Check the retirement record

   Confirm the credits are marked as retired, with the quantity, date and serial numbers you were sold.

4. 4

   Step 4: Check the beneficiary

   Look for your name or your organisation’s name. If it is hidden, ask the seller to show it.

5. 5

   Step 5: Check the project and methodology

   Read the project page and its methodology, including whether credits from it can carry the CCP label.

Where to look: public registries by standard

Each standard keeps its own registry. Use the one that issued your credits:

• Verra (VCS): the Verra Registry tracks the generation and retirement of every Verified Carbon Unit ^{Source 2}.
• Gold Standard: the Impact Registry is where Gold Standard credits are issued, held, transferred and retired, with a unique serial number for every credit ^{Source 4}.
• ACR: ACR’s public registry is at greentrace.ice.com/acr ^{Source 5}.
• Climate Action Reserve (CAR): the Reserve links its public registry from its registry guide ^{Source 6}.
• Puro.earth: the Puro Registry covers Puro’s carbon removal certificates (CORCs) ^{Source 7}.
• Isometric: the Isometric Registry is Isometric’s platform for public reporting of credit issuances and for retiring credits against public claims ^{Source 8}.

Logos identify the organisations named; no endorsement is implied.

What the retirement record tells you

The retirement record is your proof. On the Verra Registry, a public retirement record shows the serial numbers, the retirement reason, details of the reason and the beneficial owner; the last three are optional and can be kept private by the account holder^{Source 3}.

The card above is an example, not a real record. Compare each field with what you were sold:

• Serial numbers: they must match exactly. A range such as 000118–000129 means 12 credits.
• Quantity: the number retired should equal the number you paid for.
• Beneficiary: your name, or your organisation’s, so nobody else can claim the same tonnes.
• Date and vintage: the retirement date, and the vintage (the year the reduction or removal happened).

For background on what retirement means, see carbon credit retirement.

Check the methodology and the CCP label

A real, retired credit is only as good as the method used to count it. The ICVCM’s 10 Core Carbon Principles set a quality threshold, and credits that meet it can carry the CCP label^{Source 9}. The ICVCM assesses whole methodologies, and it has turned some down:

• In November 2024 it approved three REDD+ methodologies, including Verra’s VM0048, and said credits from Verra’s older REDD+ methodologies would not be able to receive the CCP label^{Source 10}.
• In August 2024 it decided that credits from eight current renewable energy methodologies would not get the label, because they don’t test rigorously enough whether projects would have gone ahead anyway^{Source 11}.

So check which methodology your project uses, and whether the registry shows a CCP label on your credits.

Use independent ratings for more detail

Ratings agencies assess individual projects and publish how they do it. Three examples:

• BeZero Carbon assesses six risk factors: additionality, over-crediting, non-permanence, leakage, perverse incentives, and the policy and political environment. It makes headline ratings for many projects freely available^{Source 12}.
• Sylvera rates projects on three pillars (carbon, additionality and permanence) on a scale from AAA to D^{Source 13}.
• Calyx Global evaluates additionality, over-crediting, permanence and overlapping claims, using frameworks it describes as peer-reviewed^{Source 14}.

Ratings are opinions with different methods, so treat them as a second check, not a guarantee.

What if the record doesn’t match?

Small differences usually have simple explanations, such as credits retired in a batch with someone else’s or a beneficiary field left private. Ask the seller for the exact retirement link and serial range that covers your purchase, and for your name to be shown. If the seller can’t produce a record at all, or the serial numbers belong to credits that are still active or were retired for someone else, treat the purchase as unverified and stop buying from that seller.

Where to go next

Verification tells you a credit is real and yours. Whether offsetting delivers what it promises is a wider question, covered in do carbon offsets work?. When you are ready to buy, start with our guide to buying carbon credits, and use the credits-needed calculator to work out how many credits you need.